Quantitative assessment of muscle injury by 23Na magnetic resonance imaging

Background: Na-23 magnetic resonance imaging (Na-23-MRI) is able to measure Na+ in vivo in humans and allows quantification of tissue sodium distribution. We now tested the utility of Na-23-MRI technique in detecting and assessing sports-related acute muscular injury. Case presentation: We assessed tissue Na+ of both lower legs with a 3T MRI scanner using a customized Na-23 knee coil. The affected left calf muscle in an injured volleyball player showed a hyperintense Na+ signal. Follow-up measurements revealed persistently increased muscle Na+ content despite complete clinical recovery. Conclusions: Our findings suggest that Na-23-MRI could have utility in detecting subtle muscular injury and might indicate when complete healing has occurred. Furthermore, Na-23-MRI suggests the presence of substantial injury-related muscle electrolyte shifts that warrant more detailed investigation.